Sofa



FIG. 1 is a perspective view of a sofa showing our new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a right side elevation view thereof, the left side elevation view being a mirror image thereof; and,

FIG. 4 is a top plan view thereof.

Views of the sofa not shown in the figures form no part of the claimed design. 

CLAIM The ornamental design for a sofa, as shown and described. 